1. Field of the Invention
This invention relates to a trigger assembly for firearms which is easily adjustable for military, hunting, and competition shooting and which is both safe and efficient in operation.
2. Description of the Prior Art
Over the past several centuries, a variety of trigger mechanisms have been devised for many different types of firearms and for different applications. Typically in military and hunting applications, trigger mechanisms are designed with emphasis on durability and reliability; consequently, such trigger mechanisms often have heavy trigger pull forces associated with firing the weapon. However, a heavy trigger pull forces degrades consistent accuracy and is particularly undesirable in competition shooting. Heavy trigger pull forces can result in instability of the firearm and also can fractionally delay discharge from the instant desired. It is necessary, of course, to have some trigger pull force to give the shooter feel and control of the firing process.
Those skilled in the art will appreciate that the desired trigger pull force is dependent upon type of firearm, application, and individual preference. An individual shooter might desire a medium to heavy trigger pull force when hunting, and a somewhat light trigger pull force for competition shooting. Further, a competition shooter might have a personal preference for a trigger pull force from two to twenty ounces.
There are, of course, many additional trigger characteristics which must be considered. For example, creep, overtrave1, retraction, sensitivity, lock time, and vibration are all important considerations. However, safety is perhaps as important a consideration as pull force of the trigger. Typically, the safety mechanisms are more dependable in triggers having heavy pull forces, while the safety mechanisms associated with light pull force triggers, such as competition triggers, are often unreliable.
For example, in typical Mauser-type bolt-action rifles, a striker or cocking piece is held in the cocked position by a sear, with the sear in turn supported by a trigger piece. The metal surface interface between the cocking piece and sear carries the main spring load. 0f course, there is a large frictional force associated between the meeting of these two metal surfaces. Typical adjustments to the trigger to lighten or vary the trigger pull force include adjusting the trigger spring or reducing to a minimum the mating surface area of the joinder between the cocking piece and the sear.
Another method of reducing trigger pull force is the so-called "multiple-lever" approach. For example, in the Remington "2-ounce" trigger, a third lever is interposed between the trigger piece and the sear to reduce the contact load carried by the trigger piece. In this arrangement, the mating surface between the cocking piece and the sear carries the large (about 25 pounds) mainspring load, while the mating area between the cocking piece and third lever carries a substantially reduced load. Other multiple lever triggers have been devised, such as the Canjar trigger (U.S. Pat. No. 4,028,835) and the Anshutz trigger (U.S Pat. No. 3,950,876).
A major problem associated with multiple lever triggers is that they merely substitute multiple sliding or sear mating surfaces. Particularly where the engagement area of these sear mating surfaces is reduced to lighten trigger pull forces, excessive wear or rounding of the mating surfaces is the inevitable result. Such wear at the sear engagement surfaces results in non-repetitive, unreliable and unsafe trigger operation. This is a particularly critical problem when the trigger is not adjustable for wear.
Another difficulty with typical trigger mechanisms is that they are either not adjustable, or only adjustable over a narrow range of trigger pull forces.
Still another problem with past trigger assemblies is the provision for adequate safety mechanisms. Particularly where the sear mating surfaces have been minimized for light pull forces, inadvertent discharge can easily result from wear of the sear mating surfaces and jolts to the firearm.
Thus, it would be a significant advance in the art if a trigger assembly were devised which allowed for adjustment of trigger pull forces over a wide range to accommodate both hunting, military, and competition shooting. Further, it would be an advance if such a trigger assembly were adjustable to individual preference. Additionally, an adjustable trigger assembly having a reliable safety mechanism would be a significant improvement in the art.